Testing Three of Disc Golf's Most Common Design Myths 

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Agreed! Thanks Colin!

Maybe more 3d printed molds than discs though.

I guess the stiffness of 3d printing can be good for consistency

@@joeillingworth1141 Also I think it's great to be able to print the disc first to that you can see how it flies and feels first before committing to making a mold

Yes!! I was truly hoping you'd pop up here 👏 And I couldn't agree more: you've written some fantastic stuff - highly recommend!

That would be so sick

Or the guy that made a basketball basket in his basement which perfectly catches the ball no matter where you throw it.

@@leksasdf yes!🙌 stuff made here I think he’s called. Might be easier to collaborate with him🤖

@@leksasdf Stuff Made Here?

@@leksasdf our dream came trough🤩 stuff made here made a disc golf machine🤩🤩

Thanks a ton man! 🤘

Thanks Sean! I truly appreciate the feedback, man.

The scratches and dents generate minuscule vortices along the surface of the disc which causes the disc to displace more air, resulting at higher speeds results in greater lifting force. It also allows the air to deflect off the bottom of the nose with less friction, decreasing the fading force. Any delamination on top and you’re no longer generating as much lift with the airflow off the back of the disc, which is going to make a disc much more stable as with a nose-up throw.

@@MaxLBogue Oooooh this is a very interesting topic! Can you elaborate more? So my understanding is that center of lift (CoL) affects the high speed stability. Forward of the Center of Gravity (CoG) will be overstable, equal to CoG will be stable and behind CoG will be understable. So are you saying that the micro scratches on the nose will increase the turbulence over the disc which will prevent the the flow from separating early and therefore the average lift will move further back behind the CoG, making the disc less stable? Are you also saying nose up shots will have increased separation due the angle of attack and causing the opposite affect with overstable flight. Is that why discs fade/stable up as they slow down because their angle of attack is affectively increasing? And why do discs become more [edit] unstable at higher velocity? Is it due to lower angle attack = more attached flow or is the higher Reynolds number increasing turbulence = more attached flow? Or both. Sorry for all the questions 😅

@@snikwahjets Yes, CoL as a combination of the lifting forces on the front edge and back edge of the disc as balanced with the CoG is what causes turn and fade through gyroscopic precession. The airflow pushing off the nose and off the back causes these two forces, simply speaking. The faster the disc, the greater the airflow, and these forces end up balancing differently at different speeds. The microvortices that scratches and dents cause function similarly to dimples in a golf ball, which in both cases allow the flying objects to displace more air with less friction. Especially in the golf disc, the increased laminar airflow allows for a greater lifting force and the decreased delamination contributes greatly to trailing edge lift as well. Nose up shots cause immediate delamination, thus the airflow off the trailing edge is minimal and very little lift and ahyzer turn are generated. Discs that are fading are generally falling onto the air, yes. This exposes more surface and therefore drag area of the underside of the nose. This is why a disc that stalls high will fade hard. Once they have dipped their edge, however, the disc will once again have a low angle of attack and gains stability as it descends. It’s a myth that faster discs are more stable. Faster discs actually have less high-speed stability, because as their CoL gets further from their CoG, their less flywheel-like gyroscopic configuration has decreased rotational inertia to resist precession. It is true that overstable drivers can be more overstable than overstable mids or putters, but this is mainly due to the greater surface area of the concave rim which tends to have quite a high PLH on those discs as well, and their relative inability to gyroscopically resist the more intense fading forces generated. All high-speed drivers all have a very wide rim under the nose which contributes to low-speed fade. Other discs do not expose nearly as much lifting surface underneath when their angle of attack changes, so drivers will always fade more. If you can, try throwing your midranges and putter as hard as you throw a distance driver and see if you notice how much more neutral they can be. Unfortunately the model of an airfoil is not particularly accurate in this context. This is a really thorough overview www.research.manchester.ac.uk/portal/files/54511821/FULL_TEXT.PDF I don’t mind the questions, I think this is really intriguing stuff and answering questions bolsters my own understanding.

@@MaxLBogue whoops I typoed the last question. Meant to say discs become "unstable" as they are "thrown" at higher speeds. But you kind of answered it anyway. By the way I downloaded that paper an realised I'd already glanced at it before. Haha. Pretty good stuff though. Reading it properly this time. 👌

@@snikwahjets Most of why the discs are "unstable" at those higher speeds is the increased airflow; basically, more speed means more lift and thus more turn. This is why molds that "hold a line", so to speak, are so valued: it means they can stay on one predictable path at various speeds, from release to target, without turning over too much off the rip or getting too stable on the finish. Trust me, I've spent a lot of time myself trying to parse through the technical stuff in there and other write-ups to reach an intuitive understanding for myself, and various others that I can share with people at different levels of long-windedness. That paper is the most consistent with my observations and the most complete on a technical level. If you play, it's really worth it to learn this stuff, at least on a qualitative level. Analyzing and predicting my shots from a practically modeled perspective rather than guesswork based solely on the feel I have for my discs has been a massive boon to my game.

Thanks Tim! 🤘

The bead is mostly aerodynamic too. It makes the disc less aerodynamic and adds drag. It slows down faster, which means it’s spending more of its flight time at lower speed. And discs fade at low speeds.

Also why discs glide out when they're fading rather than crashing nose-first into the ground every time: once they're fading hard enough, they're "nose down" with respect to the airflow across them, thus less drag force is applied to the underside of the nose. Understable discs don't need to be very nose-down to balance this out, so they can be great at coming way back on hyzer lines.

@@MaxLBogue In fact, a fading disc is going nose-up very strongly - that is what gyroscopic precession is! The disc goes nose up, which causes its airspeed to fall, drag to increase, the center of lift to shift to the right and move backwards, and it goes left accordingly. It's worth knowing that discs on a hyzer angle are always climbing through the air they are in (even if only slightly), and discs on an anhyzer angle are always descending through the air they are in. That's just the way discs work. This is why you putt with an anhyzer angle into a headwind, so the disc can't be lifted by its hyzer angle, and then fly 20-metres away!

Your story would be more compelling if you used the appropriate terms of "mechanical lift" and "Bernoulli lift". And you're wrong, sorry. The real reason high parting lines produce overstable discs is due to the reduction (or total elimination) of Bernoulli Lift across the top surface of a disc. And so a disc with a very high parting line (like Stiletto, Tilt, and Justice) is NOT a gyroscopically-stabilised flying disc, but rather a gyroscopically-stabilised ballistic disc. The difference is extreme.

@@Chris.Davies Having air pushing up on the front edge causes a force that precesses into fade. The more nose-up the disc, the greater the surface area this front edge presents to the airflow and the more lifting force will be applied there. The edges of the disc are where all the action is at because that is where the airflow is strongly redirected, thus creating higher forces; the Bernoulli effect is fairly negligible. Dominess mostly affects glide, as overstable discs can be quite glidey. A Force, a CB3 or a Heimburg destroyer are all good examples of very domey and glidey, yet very overstable discs. I’ve mostly based my understanding on this paper: www.research.manchester.ac.uk/portal/files/54511821/FULL_TEXT.PDF which does not model the disc as a standard airfoil, as you seem to do. I’d ask you this about your model: why do understable discs glide out of a hyzer rather than fading as hard as overstable discs? It seems like the center of lift should continue to shift for any disc on a hyzer angle, but understable discs do not crash like that would imply. The other thing I'd challenge is that discs on an anhyzer angle are always descending. How do discs fade out of flex lines if this is the case, should they not turn over the instant they get into anhyzer angle?

Thanks for the in depth analysis @bahaako1 🙌

The Baobab is another killer example! So wild 🤣

@@TrashPandaDiscGolf Definitely. I figure that just about any disc that has some kind of depression on the top side of the flight plate will likely experience the Bernoulli effect. Pigs, Rhynos, GT series discs, Madrone, Manzanita, Baobab, Berg, Stego, Crater. So on, so forth. The Tilt is particular in the same example you expressed about the mould line. That's completely level to the flight plate, including an aggressive bottom rim profiling. It steals it's glide from itself.

Hey Bryan! "More stable for longer" has more to do with the lifetime of the disc than how it flies on any one throw.

@@TrashPandaDiscGolf I wrote that midway in the video 🤦‍♂️. I see why school wasn’t my thing lol

It's actually recycled ABS - but yes! TPU would be great with a change of equipment.

Yep. Back in the olden days, if you had to replace a lost disc with a new one during a tournament, you were gonna have a tough day. We'd "scuff it up" on the concrete or asphalt just a little bit and that would help it fly more like a beat-in one right off the bat. Was that legal? Eh......kinda. Someone called me on it once, so I just looked him right in the eye and chucked it across the parking lot and said "Oopsie, that was a major grip-lock."

A little birdy told me this may come up in the future. But just a simple answer, if the over-mold material is a higher density than the material that makes up the rest of the disc, then absolutely the weight distribution of the disc is shifted outward. Whether that increased gyroscopic affect really changes flight characteristics significantly, well, hard for me to say. I suspect the answer is complicated. The larger the rotational moment of inertia of an object (more weight further from the axis of rotation), the harder it is to get it to spin up in the first place, but the more it wants to keep spinning without slowing down from drag. The lower the rotational moment of inertia (more weight in closer to axis of rotation), the easier it is to get it spun up, but the faster it will slow down again. So, in pure theory, an over-molded disc should take more effort to get it spinning at the same RPM as an non over-molded discs, but it should resist shedding rotational speed better. That could lead to different flights just from different throwers being able to put more or less spin into a disc. Aerodynamics is a complicated but fascinating subject.

Great question! Chris answered it super well, so I have nothing to add other than: Disc Busters part 2?! 😉

Thanks Brandon!

@H K Aerodynamics are definitely guilty for how discs fly. However, so am I alongside them.

Absolutely! I've watched that video more times than I can count 😉

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stability wise, the dome doesn't affect it, the shrinkage rate does. Shrinkage rate across a certain plastic might affect dome at the same time it affects the parting line. That affect would be different even between say opto and champion, which are different even though they're similar.

Just do it!

No they don't. A bead doesn't make a disc deeper, it merely adds material above the bottom of the rim, to reduce wear, and keep the disc flying more stably longer in its life.

This depends on how you add the bead. You can add it in such a way that it does make the disc taller, or in a way that doesn't change height. All depends on how you add the feature. In the case of this video the bead was added in a way that did not change the height.

@@Chris.Davies It depends on how the bead changes the shape of the nose. If more air ends up being directed downwards at a more intense angle, the bead will cause extra stability; if not, no changes will occur. Good examples are the Ion, the Judge, and the Wizard, which are all more stable than their beadless counterparts the Anode, the Warden, and the Warlock, respectively. The bead can, in fact, raise parting line if it is pasted directly around the bottom edge of the rim, as in the Gator and the microbeaded Caiman, and the Mortar without the bead, which go in order of most to least overstable. You can compare the Gator to its more OS cousin the Croc, which replaces the bead with a concave underside.

@@MaxLBogue nice examples!

The only relevant question is, "What's the correct dome for the shots I want to make with Disc X?" Generally speaking, if a disc has a "heartbeat" when you pop the dome, then it's a glidey disc.

@@Chris.Davies but there still has to be an optimal shape for the dome that gives the highest amount of glide. And I'd like to find out what that is. Maybe I will do it myself someday.

I'm not sure but I'd like to find that out as well!!

@@TrashPandaDiscGolf I think trying to get the same consistent shape with your moulded parts compared to your CAD and 3D prints will be challenging too. For example, the domey pop tops don't follow the nice CAD curve. They kind of buckle upwards depending on material shrinkage and cross section thinkness. Do you have inserts in your mould tools so you can make cheaper iterations?

While I haven't heard Dave say it, this was always my impression. To really test this one, they need to beat in a beaded disc and a headless, and then test it. That said, some people like the feel of a bead, some don't. That's definitely the most important factor in choosing beaded vs beadless.

They 3d print their original design to nail it down and send to pdga for approval. Only after that do they injection mold their "prototype".

We committed to having recycled discs available to the public in 2022!

Same! laugh 😅

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Not illegal at all! Løft's new Bohrium is exactly that ..which you may be seeing on the channel quite soon 😏

You only have to look at a disc. And if you carry a 15cm ruler, you can measure it yourself, with a disc on a table.

Or bring a disc similar you know and compare slide by side on a flat surface. 0.5mm can make a significant difference

Since this is based on our midrange design, we aren't going to share the stl files - BUT we've got some projects in the works where we will 😉

@@TrashPandaDiscGolf Alright, I'll start working on my own designs then.... I guess Can't wait to mulch up some discs, send them your way, and get better discs

It tastes a little chalky 😉